Motherboard standoffs and teflon tape

One does not build a PC all that often, but one annoyance while doing so involves the brass standoffs that secure the motherboard to the cabinet. First you screw these standoffs into the cabinet, then you screw the motherboard into the standoffs.

The problem is torque. You want the standoff-to-cabinet fixture to be considerably tighter than the motherboard-to-standoff fixture. It is difficult to know how hard you can tighten the standoff before you strip the threading on the cabinet. However, anything less than optimal torque lets you unscrew the standoff with bare fingers.

The fix is to use plumber's teflon tape in the threads, in the same way it is used in plumbing work. The photo below shows the roll of tape and a standoff.

The trick is to wrap an optimal length of tape tightly and uniformly without bunching, so that the threads show through, and wrap in the correct direction/sense so that when you screw in the standoff, the tape gets only tighter. The photo below shows how.

The finished product, before screwing into the cabinet, is shown below. Observe that plumbing tape is generally wider than the standoff threads, so there is a small excess length of tape beyond the end of the threading.

This is actually essential for clean threading into the cabinet. Insert the protruding teflon shaft into the cabinet hole, align perpendicular to the cabinet plane, and tighten. With some practice you will get the length of tape right so that, right from the second turn, considerable torque will be needed to keep driving the standoff into the cabinet. (If you must remove and apply new tape, remove the old tape thoroughly, leaving no hair-like residue behind.)

The final photo above, from the outer side of the motherboard tray, shows the securely installed standoff with the residual teflon shaft sticking out. It can now be snipped off for a cleaner look.

One legitimate concern is whether this technique breaks the ground paths between the motherboard PCB and the cabinet. Not so. Even 20 layers of teflon add up to something incredibly thin, and the threads cut right through them to establish secure contact. We are just packing the valleys, which would otherwise be air gaps, with stuff to tighten up the works. Still, it's a good idea to check with a continuity tester and/or install one standoff without teflon tape.